Detection and identification of the oxidizing species generated from the physiologically important Fenton-like reaction of iron(II)-citrate with hydrogen peroxide

Near UV and Visible Light Photodegradation in Solid Formulations: Generation of Carbon Dioxide Radical Anions from Citrate Buffer and Fe(III)

Near UV and visible light photodegradation can target therapeutic proteins during manufacturing and storage. While the underlying photodegradation pathways are frequently not well-understood, one important aspect of consideration is the formulation, specifically the formulation buffer. Citrate is a common buffer for biopharmaceutical formulations, which can complex with transition metals, such as Fe(III). In an aqueous solution, the exposure of such complexes to light leads to the formation of the carbon dioxide radical anion (•CO2-), a powerful reductant. However, few studies have characterized such processes in solid formulations. Here, we show that solid citrate formulations containing Fe(III) lead to the photochemical formation of •CO2-, identified through DMPO spin trapping and HPLC-MS/MS analysis. Factors such as buffers, the availability of oxygen, excipients, and manufacturing processes of solid formulations were evaluated for their effect on the formation of •CO2- and other radicals such as •OH.

Hydroxyl radical generations form the physiologically relevant Fenton-like reactions

Iron(II) species can participate in the Fenton and Fenton-like reactions to generate the hydroxyl radical that can oxidatively damage biomolecules and induce oxidative stress in biological systems. Many diseases, including neurodegeneration, cardiovascular disease and cancer, are associated with oxidative stress. However, it is proposed recently that hydroxyl radical would not be generated from the Fenton reaction under physiological conditions and thus would not cause oxidative stress in biological systems. This proposal may cause confusion for understanding oxidative stress and can also have impact on therapeutic strategies for the diseases associated with oxidative stress. In this Mini-review, the up-to-date convincing evidences of hydroxyl radical generation from the physiologically relevant Fenton-like reactions of the iron(II) complexes with physiological ligands in human blood plasma, including histidine, citrate and phosphate, are succinctly reviewed. The oxidative damages caused by hydroxyl radical to biomolecules and cells are briefly summarized. These findings strongly challenge the above proposal.

Jing-Fang n-butanol extract and its isolated JFNE-C inhibit ferroptosis and inflammation in LPS induced RAW264.7 macrophages via STAT3/p53/SLC7A11 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine has accumulated valuable experience in the treatment of inflammatory diseases caused by Ferroptosis. Jing Jie and Fang Feng are two warm acrid exterior-resolving medicinal herbs that play an important role in the prevention and treatment of inflammatory diseases. The pairing of the two forms a drug pair (Jing-Fang) that shows significant advantages in fighting oxidative stress and inflammation. Whereas, the underlying mechanism needs to be further improved.

AIM OF THE STUDY

In this study, the anti-inflammatory effect of Jing-Fang n-butanol extract (JFNE) and its isolate C (JFNE-C) on LPS-induced RAW264.7 cells and the regulation effect on ferroptosis were investigated, and also the mechanism of STAT3/p53/SLC7A11 signal pathway-related to ferroptosis.

MATERIALS AND METHODS

Jing-Fang n-butanol extract (JFNE) and its active isolate (JFNE-C) were extracted and isolated. LPS-induced inflammation model in RAW264.7 cells was established to assess the anti-inflammatory effect and ferroptosis mechanism of JFNE and JFNE-C. The levels of interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) were measured. The activity levels of antioxidant substances such as glutathione (GSH), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were measured. Flow cytometry, immunofluorescence and transmission electron microscopy were used to assess ROS level, ferrous iron content and mitochondrial morphological changes. Through administration of Ferrostatin-1 (Fer-1), an ferroptosis inhibitor, to verify the role of JFNE and JFNE-C in regulating ferroptosis in resistance to the inflammatory response. Western blotting was used to determine whether the JFNE and JFNE-C exerted effectiveness by modulating the STAT3/p53/SLC7A11 signaling pathway. In addition, the important role of STAT3/p53/SLC7A11 signaling pathway in drug regulation of ferroptosis and inflammatory response was further validated by administration of S3I-201 (STAT3 inhibitor). Finally, high performance liquid chromatography-mass spectrometry (HPLC-MS) was used to determine the major active components of JFNE and JFNE-C.

RESULTS

The results showed that treated with JFNE-C significantly reduced the contents of interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) in the supernatant of LPS-induced RAW264.7 cells. The pretreatment with JFNE and JFNE-C significantly decreased intracellular oxidative stress levels, including reductions of ROS and MDA levels, and increases of GSH-Px, SOD and GSH levels. In addition, JFNE and JFNE-C obviously reduced intracellular ferrous iron level, and JFNE-C was effective in alleviating mitochondrial damage which includes mitochondrial shrinkage, increase of mitochondrial membrane density and reduction and absence of cristae. Further results indicated that JFNE-C showed a reduction of p53 and p-p53 protein levels in LPS-induced RAW264.7 cells, while significantly increasing the protein expression levels of STAT3, p-STAT3, SLC7A11 and GPX4. Besides, JFNE-C contains key active substances such as 5-O-Methylvisammioside, Hesperidin and Luteolin. Remarkably, this is different from JFNE, which is rich in nutrients such as sucrose, choline and various amino acids.

CONCLUSION

These results suggest that JFNE and JFNE-C may exert anti-inflammatory effect through activating the STAT3/p53/SLC7A11 signaling pathway to inhibit ferroptosis.

Reactive Oxygen Species and Antioxidant System in Selected Skin Disorders

The skin has a solid protective system that includes the stratum corneum as the primary barrier and a complete antioxidant defence system to maintain the skin's normal redox homeostasis. The epidermal and dermal cells are continuously exposed to physiological levels of reactive oxygen species (ROS) originating from cellular metabolic activities. Environmental insults, such as ultraviolet (UV) rays and air pollutants, also generate ROS that can contribute to structural damage of the skin. The antioxidant defence system ensures that the ROS level remains within the safe limit. In certain skin disorders, oxidative stress plays an important role, and there is an established interplay between oxidative stress and inflammation in the development of the condition. Lower levels of skin antioxidants indicate that oxidative stress may mediate the pathogenesis of the disorder. Accordingly, the total antioxidant level was also found to be lower in individuals with skin disorders in individuals with normal skin conditions. This review attempts to summarise the skin oxidant sources and antioxidant system. In addition, both skin and total antioxidant status of individuals with psoriasis, acne vulgaris, vitiligo and atopic dermatitis (AD), as well as their associations with the progression of these disorders will be reviewed.

Pyrroloquinoline quinone modulates YAP-related anti-ferroptotic activity to protect against myocardial hypertrophy

Background: Pyrroloquinoline quinone (PQQ) has been reported to exhibit cardioprotective and antioxidant activities. Accordingly, this study was developed to explore the effects of PQQ treatment on myocardial hypertrophy and the underlying mechanism of action governing any observed beneficial effects.

Methods: A transverse aortic constriction (TAC) model of myocardial hypertrophy was established in vivo using C57BL/6 mice, while neonatal murine cardiomyocytes were stimulated with phenylephrine (PE) as an in vitro validation model system.

Results: Treatment of TAC model mice with PQQ significantly suppressed myocardial hypertrophy and fibrosis, in addition to inhibiting the ferroptotic death of hypertrophic myocardial cells in vivo. Subsequent in vitro analyses revealed that treatment with PQQ was sufficient to significantly alleviate PE-induced hypertrophic activity and to prevent ferroptotic induction in these primary murine cardiomyocytes. At the mechanistic level, PQQ was found to promote the upregulation of Yes-associated Protein (YAP), to suppress YAP phosphorylation, and to drive the nuclear translocation of YAP within hypertrophic cardiomyocytes. The use of a specific siRNA construct to knock down YAP expression in vitro further confirmed the ability of PQQ to protect against myocardial hypertrophy at least in part through anti-ferroptotic mechanisms.

Conclusion: PQQ can regulate the pathogenesis of myocardial hypertrophy through the induction of YAP-related anti-ferroptotic activity, highlighting the potential value of PQQ as a novel therapeutic agent capable of slowing or preventing the progression of myocardial hypertrophy and thus delaying the onset of heart failure.

Cold Plasma Irradiation Regulates Inflammation and Oxidative Stress in Human Bronchial Epithelial Cells and Human Non-Small Cell Lung Carcinoma

Atmospheric pressure cold plasma has shown multiple biological effects of anti-bacteria and anti-cancer. In this study, the effect of atmospheric pressure cold plasma on respiratory inflammation and oxidant stress is explored. Tunicamycin was used to stimulate human bronchial epithelial cells (HBECs) and A549 cells for inflammatory response and oxidative stress, followed by atmospheric pressure cold plasma treatment. For HBECs and A549 cells, atmospheric pressure cold plasma was able to alleviate tunicamycin-induced cell proliferation inhibition, inflammation and oxidant stress, and enhance nuclear factor-erythroid-2-related factor 2 (NRF2) pathway activation. Moreover, NRF2/ARE (anti-oxidant response elements) pathway was involved in the regulation of atmospheric pressure cold plasma on tunicamycin-induced oxidative stress. These results suggest the positive effect of atmospheric pressure cold plasma on inflammation and oxidant stress of respiratory system, indicating the therapeutic potential of atmospheric pressure cold plasma for respiratory diseases.

Fenton-like reaction of the iron(II)-histidine complex generates hydroxyl radicals: implications for oxidative stress and Alzheimer's disease

The hydroxyl radical (˙OH), generated from Fenton/Fenton-like reactions of iron(II) species in biology, can oxidatively damage biomolecules, inducing oxidative stress and diseases. However, this common understanding has been questioned recently after a carbonate radical was observed from the Fenton-like reaction of the iron(II)-carbonate complex. Herein, we report that the Fenton-like reaction of the iron(II)-histidine complex, one major iron(II) species in blood plasma, can occur at neutral pH to generate ˙OH, not iron(IV). Our findings and critical analyses on relevant studies clarify the above doubt, reveal a new pathway of causing oxidative stress by the iron(II) species, and have implications for Alzheimer's disease.

The molecular mechanisms of ferroptosis and its role in cardiovascular disease

Ferroptosis is a programmed iron-dependent cell death characterized by accumulation of lipid peroxides (LOOH) and redox disequilibrium. Ferroptosis shows unique characteristics in biology, chemistry, and gene levels, compared to other cell death forms. The metabolic disorder of intracellular LOOH catalyzed by iron causes the inactivity of GPX4, disrupts the redox balance, and triggers cell death. Metabolism of amino acid, iron, and lipid, including associated pathways, is considered as a specific hallmark of ferroptosis. Epidemiological studies and animal experiments have shown that ferroptosis plays an important character in the pathophysiology of cardiovascular disease such as atherosclerosis, myocardial infarction (MI), ischemia/reperfusion (I/R), heart failure (HF), cardiac hypertrophy, cardiomyopathy, and abdominal aortic aneurysm (AAA). This review systematically summarized the latest research progress on the mechanisms of ferroptosis. Then we report the contribution of ferroptosis in cardiovascular diseases. Finally, we discuss and analyze the therapeutic approaches targeting for ferroptosis associated with cardiovascular diseases.

Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review

Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of the application of CAs to enhance the Fenton process for the remediation of soils polluted with the most common organic contaminants, especially for a deep understanding of the activation mechanisms and influential factors. The existing shortcomings and research needs have been highlighted. Finally, future research perspectives on the use of CAs in MF and recommendations have been provided.

Iron and oxidizing species in oxidative stress and Alzheimer's disease

Iron species can participate in the Fenton or Fenton-like reaction to generate oxidizing species that can cause oxidative damages to biomolecules and induce oxidative stress in the body. Furthermore, iron accumulation and oxidative stress have been shown to associate with the pathological progression of neurodegenerative disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). In this review, the role of iron species in generating the most deleterious free radical species (ie, hydroxyl radical) and effects of this species in causing oxidative stress in vivo are described. The implications of oxidative stress and the recently recognized cell death pathway (ie, ferroptosis) to AD are addressed. Strategies to combat this neurodegenerative disease, such as iron chelation and antioxidant therapies, and future research directions on this aspect are also discussed.